1. Field of the Invention
The present invention relates to a wireless communication system, and more particularly, to a W-CDMA (Wide band-Code Division Multiple Access) wireless communication system.
2. Background of the Related Art
Generally, a wireless communication system such as a WLL (Wireless local loop) adopts a CDMA multi-connection method that has a large accommodation capacity for subscribers compared to other connection methods. Unlike the existing narrow band CDMA method, a wide band CDMA method is capable of implementing an ISDN (integrated services data network) service and a packet communication network, as well as transferring a call, a facsimile, and data.
FIG. 1 is a schematic block diagram of the W-CDMA WLL system, which includes an RIU (radio interface unit) 20 for receiving a signal from a subscriber terminal 10 of a user and wirelessly transferring it to a base station via antennas. The base station includes a RP (radio port) 30 for handling connection and release of a signal wirelessly with the RIU 20. An RPC (radio port controller) 40 connects a call link between the RP 30 and a WLL switching system 50, and a WLL switching system 50 establishes a call link with an existing PSTN (public switch telephone network) 60.
In the WLL system constructed as described above, a forward direction power from the RP 30 to the RIU 20 includes a pilot channel, a synchronization channel, a paging channel, a traffic channel and a signal channel. Accordingly, the RP 30 is able to heighten a communication efficiency by adequately controlling a power ratio between the channels with a limited forward direction power.
Generally, there is a standard for constantly maintaining and using the ratio of each channel that constructs the forward direction power or a reverse direction power in the CDMA wireless communication system. For example, a forward direction power defined in an international standard, IS-97-A, presented by Qualcomm Co., is constructed such that 20% is occupied by a pilot channel and the remaining 80% is occupied by the synchronization channel, paging channel and traffic channel (total forward direction power equals 100%).
The power ratio of IS-97-A must be altered in a W-CDMA system to account for the power of the signal channel. In this respect, the power value of the signal channel is defined to be different depending on the data speed of the traffic channel.
The RP 30 of the background W-CDMA WLL system determines a power ratio of each channel on the basis of the entire traffic channel that it can receive, and controls the forward direction power of each channel by applying these power ratios to the fixed power value.
However, the background art has a problem in that, since the previously established power ratio is used for each channel, an actual power ratio is determined differently depending on the number of individual traffic channels currently connected to the RP 30. For example, if the power ratio of each channel is determined based on the assumption that 30 individual traffic channels in total are connected, a relative power ratio of each individual traffic channel actually received by the RIU 20 would be much different when 10 individual traffic channels are actually connected to be operated.
Thus, a problem arises in that the power ratio would unavoidably offend the standard as defined, and thus, the smaller the number of actual individual traffic channels becomes, the smaller the power ratio of the traffic channel to the other channels becomes, which negatively affects its communication quality.
An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
An object of the present invention is to improve the power ratio.
Another object of the present invention is to improve the power ratio in a forward direction.
A further object of the present invention is maintain a constant power ratio.
Still another object of the present invention is to provide a method for controlling the forward direction power ratio in a W-CDMA wireless base station in which the power ratio of each channel is adjusted according to the number of traffic channels so that a constant power ratio is maintained regardless of the number of the traffic channels.
To achieve these and other advantages and, in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for controlling a forward direction power ratio of a plurality of channels in a wireless base station including the steps of: recognizing a variation in the number of traffic channels; recognizing a data transfer speed of the traffic channel; determining a power ratio for each channel according to the number of traffic channels and the data transfer speed; and re-adjusting an existing power ratio according to the determined power ratio for each channel.
To further achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a wireless communication system including: a remote system that receives and transmits information data; and a base station that receives and transmits information data, wherein communication between the remote system and the base station is established by a plurality of channels including a first channel, a power ratio for the plurality of channels being based on a number of individual first channels and a data transfer rate of the first channel.
To still further achieve these and other advantages and in accordance with the purpose of the present invention, as is embodied and broadly described herein, there is provided a base station including: a radio frequency device that converts signals to and from a wireless signal; an antenna that transmits and receives the wireless signal; and a controller that digitizes a signal to be transferred to the radio frequency device, spreads it, and converts to an analog signal, and controls a first channel power and a second channel power according to a power ratio determined based on a number of individual it first channels.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.